The art of the present invention relates to ultrasonic surgical devices in general and more particularly to a high efficiency ultrasonic tip for use in neurosurgery and other surgical disciplines. The use of ultrasonic aspirators in neurosurgery is well understood and recognized in the field of neurosurgery. Ultrasonic aspiration provides for emulsification and in situ evacuation of intracranial tumors. In this way, retraction of eloquent brain is minimized, while disruption and removal of tissue is advanced.
Prior art ultrasonic aspirators typically utilize a tubular tip having a threaded connecting end and a contacting end. The threaded connecting end attaches to an ultrasonic generator handpiece which injects ultrasonic energy into the tip and further allows for aspiration through said tubular tip. Said energy causes said tubular tip to elastically elongate and retract along the tubular axis at a frequency corresponding to the ultrasonic excitation frequency of the ultrasonic generator. Often the contacting end of said prior art devices is best described as a planar cut perpendicular to the tubular axis of the tubular tip. In other words, the contacting end is simply a flat cut at the tube end which is again perpendicular with the lengthwise tubular axis of the tip.
Prior art ultrasonic aspirators for neurosurgery rely solely upon the phenomenon of cavitation to reduce tissue to its emulsified form. That is, the contacting end of said prior art extends and retracts up to 350 microns at a rate from 20 to 50 kilohertz, thereby producing an ultrasonic field which creates a low pressure cavitation zone at the contacting end. The resulting low-pressure zone at the tip of the aspirator causes cell wall collapse and release of intracellular fluid which creates an emulsate. Therafter, said emulsate is aspirated through said tubular tip via the action of an aspiration system connected inline with said ultrasonic generator handpiece and said tubular tip.
This prior art method of emulsification and aspiration is extremely safe, as it maintains some selectivity of destruction and limits disruption of tissues with low water mass. However, there are times when this selectivity becomes problematic. Fibrotic meningiomas and calcified tumors are minimally affected by the aforementioned cavitation phenomenon thereby dramatically increasing operative time or in some instances completely prohibiting the use of ultrasonic aspiration for their removal. Hence, the benefits of in situ evacuation are lost on these pathologies. Likewise, tumors previously treated with radiosurgery can often find themselves xe2x80x9cweldedxe2x80x9d to surrounding pathology. (i.e. dura, bony prominences within the skull base, etc.) Again, the aforementioned limitations of ultrasonic aspiration apply.
The present art utilizes an ultrasonic field to produce the aforementioned cavitation along with a cutting action at the contacting end of the uniquely designed tubular tip. That is, the present art provides in situ evacuation of the aforementioned intracranial tumors. The aforesaid cutting is promoted at the ultrasonically excited contacting end when the contacting end is not perpendicular to the tubular axis of the tubular tip. In other words, since the ultrasonically excited contacting tip longitudinally extends up to 350 microns, a slicing or mechanical cutting action may be promoted when the contacting tip has an angle relative to the tubular axis. Unfortunately, a simple angle on the contacting end relative to the tubular axis does not promote efficient aspiration or an optimum ultrasonic field.
The present invention represents a tubular tip having a xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d shaped cut or notch within the contacting end which provides optimum slicing or cutting action while also maintaining asymmetrical handpiece operation, an optimum ultrasonic cavitation field, and optimum aspiration. That is, the present invention represents a tubular tip which is utilized in the aforementioned prior art ultrasonic generator handpiece and provides the traditional ultrasonic and aspiration benefits and allows a surgeon to use the ultrasonic handpiece in any rotational axis position. The tubular tip has a connecting end and a contacting end, yet the contacting end is uniquely shaped to provide the aforementioned cutting action. In a preferred embodiment, said contacting end contains a substantially xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d shaped cut which provides the desired cutting or slicing action along with a desirable locus for uniform aspiration and ultrasonic field generation. The base of the aforementioned xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d cut is placed opposite the contacting end, or towards to the connecting end.
Accordingly, it is an object of the present invention to provide a high efficiency ultrasonic surgical aspiration tip having a contacting end which promotes mechanical cutting and slicing of various tissues and other materials, including fibrotic meningiomas and calcified tumors.
Another object of the present invention is to provide a high efficiency ultrasonic surgical aspiration tip having a threaded end which functions with prior art ultrasonic generator handpieces, produces a substantially uniform optimum ultrasonic and aspiration field, and also provides the desired cavitation.
A further object of the present invention is to provide a high efficiency ultrasonic surgical aspiration tip which provides an asymmetrical ultrasonic generator handpiece operation while also promoting efficient and convenient aspiration.
To accomplish the foregoing and other objects of this invention there is provided a high efficiency ultrasonic surgical aspiration tip and method of using the same. The method and apparatus provide for a unique and desired cutting or slicing action while further providing the traditionally desired aspiration and ultrasonic field generation. In a preferred embodiment, the apparatus is claimed in conjunction with a conventional ultrasonic generator handpiece of a surgical aspirator and the method of use is claimed in conjunction with the action of surgical tissue and tumor removal.
As aforementioned, in its preferred embodiment, the present art represents a tubular tip having a connecting end, a contacting end, and a xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d shaped cut or notch within the contacting end which provides optimum slicing or cutting action while also maintaining asymmetrical handpiece operation, an optimum ultrasonic cavitation field, and optimum aspiration through the interior tube portion of the tip. In the preferred embodiment, the base of said xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d shape is positioned closer to the connecting end than the legs of the xe2x80x9cUxe2x80x9d or xe2x80x9cVxe2x80x9d. That is, the tips of the legs of the xe2x80x9cUxe2x80x9d or xe2x80x9cVxe2x80x9d represent the tip of the contacting end and face away from the connecting end. In the preferred embodiment, the connecting end comprises a male threaded portion which mates with a female threaded portion on the ultrasonic generator handpiece. Said connecting end further comprises a shoulder, away from said connecting end and toward said contacting end, which seats upon and with the mating end of the acoustic horn of the ultrasonic generator handpiece of the aspirator. Alternative embodiments may utilize attachment methods at the connecting end other than threads. These include but are not limited to mating pinned portions, welding, sweated connections, soldered connections, brazed connections, mechanical quick disconnects, and ball and detent connections.
Alternative embodiments utilize variations of the xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d cut in the contacting end. That is, a first alternative embodiment contains multiple xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d cuts at the contacting end which form in combination a serrated cut at the contacting end. Further alternative embodiments embody an asymmetrical xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d shaped cut at the contacting end. That is, one leg of the xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d is shorter or longer than the other. Still further alternative embodiments provide honed or sharpened edges on said contacting end to further the aforementioned cutting action.
In all of the aforementioned preferred and alternative embodiments of the present art a uniform and symmetric ultrasonic field is generated substantially near the contacting end and in line with the tubular axis of the tip. This desirable feature is not present in prior art devices which provide for or offer cutting action. That is, prior art devices have provided only a single or single compound angular cut on the contacting tip which does not provide a uniform and symmetric ultrasonic field at the contacting tip. That is, the prior art cut on the contacting end is asymmetrical, thereby limiting the ultrasonic energy which is transmitted to the fluid, tissue, or tumor in which it is embedded and further creating an asymmetric ultrasonic field in said medium. An asymmetric field forces the user to rotate the ultrasonic generator handpiece to place the ultrasonic field or cavitation at the desired location since the ultrasonic field does not radiate in a uniform or half-sphere isotropic manner from contacting end.
The preferred and alternative embodiments of the present art also provide the desirable optimum aspiration at the contacting end. Since the ultrasonic handpiece is substantially tubular in nature, a surgeon typically desires to utilize the ultrasonic handpiece without concern as to rotational position about the tubular axis. This is not possible with prior art tips which provide for a cutting action. Since the present art contacting end maintains a substantially planar front at the contacting end, aspiration and field generation occurs primarily inline with the tubular axis. This again, allows the user to asymmetrically position the ultrasonic generator handpiece while maintaining effective aspiration and ultrasonic cavitation effects. In toto, the present art maintains all of the prior art benefits of optimum placement and generation of the ultrasonic field and optimum asymmetrical aspiration while providing enhanced mechanical cutting action.
The present art tubular tips may be manufactured from a variety of materials which provide the desired modulus of elasticity and a sufficiently high elastic limit to withstand the transmitted ultrasonic energy. Materials include but are not limited to metals and their alloys of steel, stainless steel, titanium, and super-elastic nickel titanium. Further manufacturing materials include ceramics, composites, and plastics. The method of manufacturing the present art with the xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d cuts include but are not limited to traditional machining methods or non-mechanical machining methods such as laser cutting and electrical discharge machining (EDM).
The art of the present invention as contemplated is effective in the in situ evacuation of intracranial tumors. However, it is also capable of in situ evacuation of intervertebral disc material, thereby facilitating a minimally traumatic discectomy, and further use in ophthalmic ultrasonic surgery. It is also specifically contemplated that the present device could be used in general endoscopic surgery, including but not be limited to, surgery of the colorectal tract, biliary system, thoracic cavity, and other pathologies not mentioned. A variant of this device could further be utilized for intravitreal fragmentation of dislocated crystalline lenses.
In use, the surgeon or assistant, first installs the tip within the mating end of the acoustic horn of the ultrasonic generator handpiece. In the preferred embodiment, this is by screwing the tip into the mating end and applying the proper torque. Once installed, the surgeon may, if desired or necessary for the surgery, place an irrigation sleeve or flue around said tip aft of said contacting end before the operation begins. (The irrigation sleeve allows the handpiece to provide irrigation fluid to the surgical site through the ultrasonic handpiece.) During the surgical procedure, the surgeon places the contacting end onto or near the tissue or tumor which he or she desires to remove. Once placed, the surgeon then energizes the ultrasonic generator handpiece and the vacuum aspiration system if desired. The ultrasonic energy transmitted to the contacting end then creates a uniform ultrasonic field relative to the tubular axis of the tip. This field is of such high frequency and amplitude that the liquid or tissue surrounding it cavitates or breaks down. This allows for removal of said material through the interior tube portion of said tip via the aforesaid vacuum aspiration.